The Stryker brigade sent to Afghanistan recently has been there for three month and has had a hard time dealing with the growing Taliban use of IEDs (Improvised Explosive Device; roadside bombs and anti-vehicle mines). In that time, the brigade has lost 21 Stryker vehicles and 25 soldiers killed because of these weapons. IEDs are more effective in Afghanistan because most of the roads are unpaved, and, compared to Iraq, there are fewer roads. As a wheeled vehicle, the Stryker is less able to move cross country. Moreover, the Taliban have figured out how to adjust the pressure plates (that set off the landmines buried under dirt roads), so that they only go off when the heavy (22 ton) Strykers roll over it, not when lighter civilian vehicles do. This lessens civilian casualties, which tend to turn the locals against the Taliban (no matter how much the Taliban try to force them to do otherwise).
The Stryker brigade has had to upgrade the "counter-IED techniques" developed in Iraq, and remembered by many members of the brigade. The brigades 350 Stryker vehicles are also equipped with lots more electronics and communications equipment than earlier armored vehicles. The brigade has an initial version of the battlefield Internet that the army is slowly putting together.
The 5th Stryker brigade has seen a lot of action in add, some of it quite heavy. The protection on the Strykers has been up to the job when it comes to machine-guns and RPGs, but it takes MRAPs to handle the IEDs. The Strykers are faster, and quieter, than tracked armored vehicles. This still turns out to be a battlefield advantage, something American troops had forgotten about. The last large scale use of wheeled armored vehicles by American troops was in World War II. Some of the details of how those vehicles could be used had apparently been forgotten. A wheeled armored vehicle can more quickly move out of an ambush, or any other kind of trouble. Wheeled armored vehicles also make a lot less noise. The track laying system is inherently noisy, wheels are not. Strykers can sneak up on the bad guys, an M-2 Bradley or M-1 tank cannot. But the anti-vehicle mines on dirt roads are a wheeled vehicles worst nightmare, and requires lots of sharp eyes, and new thinking, to deal with.